Three Research Cores are proposed to facilitate interdisciplinary research into hearing and deafness at the Massachusetts Eye and Ear Infirmary. The Research Center comprises 23 investigators, all affiliated with the Eaton-Peabody Laboratory (EPL). They include clinicians and basic scientists, with academic ties to graduate programs and departments at Harvard Medical School and MIT. The Research Base covers a wide range of basic and applied research projects from peripheral mechanics to cortical processing, from in vitro systems to human patients, from animal models to neural nets. The EPL research group has a long history of fruitful collaboration based on sharing of equipment, resources and scientific expertise via a system of research cores supported by a program project grant in the 80's and 90's, and by this P30 for the last 4 years. Each of the Cores supports highly experienced personnel to 1) staff, stock, maintain and upgrade existing shared research facilities;2) train users and/or render expert technical services in these facilities;and 3) provide the necessary technical expertise to enhance research productivity and facilitate the fusion of different research approaches across the many disciplines represented in the Research Center. The three Cores and the major aims of each include 1) an Engineering Core to design, build, program and maintain data-acquisition systems, custom acoustical devices, and stimulus generation systems, and to provide a precision machining service to build custom mechanical devices for a wide variety of research applications;2) an Imaging Core to support the needs of Center investigators for digital image-acquisition and analysis, including confocal microscopy, transmission electron microscopy, computer-aided anatomical reconstruction, automation of morphometry, 3-D reconstruction/rendering, and analysis of functional imaging data;and 3) a Histology/Surgery Core to maintain existing shared facilities and assist research teams in animal surgery and histological preparation for both light and electron microscopy;and